甲烷/空气燃烧NOx排放数值模型对比  

Comparison of NOx numerical models for methane/air combustion simulations

作　　者：孙继昊 罗绍文 赵宁波[1] 杨慧玲 郑洪涛[1] SUN Jihao;LUO Shaowen;ZHAO Ningbo;YANG Huiling;ZHENG Hongtao(College of Power and Energy Engineering,Harbin Engineering University,Harbin 150001,China)

机构地区：[1]哈尔滨工程大学动力与能源工程学院,哈尔滨150001

出　　处：《清华大学学报（自然科学版）》2023年第4期623-632,共10页Journal of Tsinghua University(Science and Technology)

基　　金：国家科技重大专项(Y2019-I-0022-0021,2017-Ⅲ-0006-0031)。

摘　　要：为明确不同NOx数值模型对甲烷/空气燃烧NOx生成特性的适用性和差异性,以射流扩散火焰、旋流预混火焰、燃气轮机燃烧室为研究对象,分析了NOx后处理模型法、解耦详细反应机理法和附加NOx输运方程法对甲烷/空气燃烧NOx生成特性模拟的适用性和差异性。结果表明:火焰后方N2O的生成量较少,NO_(2)的生成量极少,NO含量占总NOx的95.00%以上;NOx后处理模型法可准确模拟火焰附近的NOx生成位置和火焰后方的NOx生成速率,但该模型低估了火焰位置的NOx生成量和生成速率,并且不能再现火焰锋面附近N2O浓度先升高后下降的变化规律;附加NOx输运方程法对火焰锋面处的NOx生成位置、生成量和生成速率的计算精度最高,但该模型低估了火焰锋面后方的NOx生成速率;解耦详细反应机理法对NOx生成特性的预测精度最差。[Objective]Correct usage of models for NOx combustion simulations can considerably reduce the computational time compared to directly coupling the detailed chemical mechanisms.Several NOx models are available:the NOx postprocessing model,decoupled detailed mechanism model,and adding NOx transport equations in flamelet generated manifold(FGM)model.However,their differences and applicability remain unclear,so choosing a model for a particular work is challenging.Therefore,the differences and applicability of these models must be verified under different situations,particularly for diffusion combustion,premixed combustion,and real combustors(partly premixed combustion).[Methods]In this study,numerical simulations were performed on a diffusion jet flame(Sandia flame D),premixed swirl flame(Cambridge swirl flame SW3),and partly premixed flame(an industrial gas turbine combustor)to thoroughly understand the differences and applicability of these three models.The turbulence and combustion models were the realizable standard k-εmodel and the flamelet-generated manifold model,respectively.The turbulence and combustion models were verified against the experimental results;furthermore,the NOx(including NO,NO_(2),and N2O)distribution and formation characteristics,as well as NOx emissions,were compared and discussed with the experimental results.For the NOx postprocessing model,O and OH radicals were treated as partial equilibrium consumption,and the turbulence-combustion interaction was modeled asβ-PDF(β-probability density function,PDF)consumption.For the decoupled detailed mechanism model,the species(excluding NOx),pressure,velocity,and temperature distributions were obtained using numerical simulation and held constant,and then NOx chemistry was solved.For the added NOx transport equation model,the three NOx transport equations of NO,NO_(2),and N2O were added to the PDF table to calculate NOx(including NO,NO_(2),and N2O).During the computation of NOx transport equations,only NO,NO_(2),and N2O were solved,and the remain

关 键 词：NOx模型 数值模拟 射流扩散火焰 旋流预混火焰 燃烧室 

分 类 号：V231.2[航空宇航科学与技术—航空宇航推进理论与工程]